Composite heat pipe structure

ABSTRACT

A composite heat pipe structure is provided. In various embodiments, the composite heat pipe structure includes an outer body and a plurality of internal heat pipes sequentially disposed in a longitudinally adjacent relationship within an interior cavity of the outer body. The internal heat pipes are sequentially thermally coupled to one another along a portion of each respective internal heat pipes so that heat absorbed at a first end of the outer body is transferred to a second end of the outer body, via the internal heat pipes, with a high rate of thermal efficiency.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/020,606, filed on Jan. 11, 2008, the disclosure of which isincorporated herein by reference in its entirety.

Additionally, the present application is related in general subjectmatter to U.S. patent application Ser. No. 11/765,140, filed Jun. 19,2007, which is hereby incorporated by reference in its entirety.

FIELD

The present teachings relate to heat pipes. More specifically, thepresent teachings relate to a composite heat pipe structure constructedof a plurality of thermally interconnected internal heat pipes disposedwithin an interior cavity of the composite heat pipe structure. Thecomposite heat pipe structure generally extends over a particulardistance for which heat is to be transferred.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Heat pipes are a heat transfer mechanism that can transport largequantities of heat with a very small difference in temperature betweenhot and cold interfaces. A typical heat pipe consists of a sealed hollowtube made of a thermally conductive material, e.g., a thermallyconductive metal such as copper or aluminum. The heat pipe contains arelatively small quantity of a “working fluid” or coolant (such aswater, ethanol or mercury) with the remainder of the heat pipe beingfilled with a vapor phase of the working fluid, all other gases beingsubstantially excluded. Heat is transferred from an evaporator end of aheat pipe to an opposing condenser end of the heat pipe by a rapidtransition of heat vaporized working fluid from the evaporator end tothe condenser end.

More particularly, heating the evaporator end of the heat pipe willcause the working fluid inside the heat pipe at the evaporator end toturn to vapor, thereby increasing the vapor pressure inside the heatpipe. Latent heat of evaporation absorbed by the vaporization of theworking fluid reduces the temperature at the evaporator end of the heatpipe. Moreover, the vapor pressure at the evaporator end of the heatpipe is higher than the equilibrium vapor pressure at the condenser endof the heat pipe. This pressure difference drives a rapid mass transferof the heated vaporized working fluid from the evaporator end to thecondenser end of the heat pipe where the vapor condenses, therebyreleasing its latent heat and heating the condenser end of the heatpipe. The condensed working fluid then flows back to the evaporator endof the heat pipe.

However, the length of heat pipes can be limited by difficultiesencountered in moving the condensed working fluid from the condenser endof the heat pipe back to the evaporator end. Therefore, in someinstances, heat pipes can contain a wick that returns the working fluidto the evaporator end by capillary action. Such wicks typically consistof metal powder sintered onto the inside walls of the heat pipe, butcan, in principle, be any material capable of soaking up the coolant.Wicks aid in returning the condensed working fluid to the evaporatorend, however, limitations in heat pipe length can still exist as aresult of difficulties in returning the condensed fluid to theevaporator end of the heat pipe.

For example, gravitational forces, or absence thereof, can impede orassist movement of the condensed working fluid from the condenser end tothe evaporator end of the heat pipe. Such gravitational limitations aregenerally a function of orientation of the heat pipe. In the case ofheat pipes that are vertically-oriented with the evaporator end down,the fluid movement is assisted by the force of gravity. For this reason,heat pipes can be the longest when vertically oriented with theevaporator end of the heat pipe below the condenser end. The length of aheat pipe will be most limited when the heat pipe is vertically orientedwith the evaporator end of the heat pipe above the condenser end. Inthis orientation, gravity attracts the condensed fluid to the condenserend of the heat pipe rather than the evaporator end. When horizontal,the maximum heat pipe length will be somewhere between the maximum heatpipe lengths in the two vertical orientations.

SUMMARY

The present disclosure provides a composite heat pipe structure that isstructured and operable to transfer heat from a first end of thecomposite heat pipe structure to a second end of the composite heat pipestructure with a high rate of thermal efficiency, i.e., with very littlethermal resistance.

In various embodiments, the composite heat pipe structure includes anouter body and a plurality of internal heat pipes sequentially disposedin a longitudinally adjacent relationship within an interior cavity ofthe outer body. The internal heat pipes are sequentially thermallycoupled to one another along a portion of each respective internal heatpipes so that heat absorbed at a first end of the outer body istransferred to a second end of the outer body, via the internal heatpipes, with a high rate of thermal efficiency.

In various other embodiments, the composite heat pipe structure includesan outer body and a plurality of internal heat pipes longitudinallydisposed within an interior cavity of the outer body such that acondenser end of each internal heat pipe is thermally coupled with anevaporator end of at least one longitudinally adjacent internal heatpipe. Therefore, heat absorbed at a first end of the outer body istransferred to a second end of the outer body, via the internal heatpipes, with a high rate of thermal efficiency.

In still other embodiments, the composite heat pipe structure includesan outer body and a plurality of internal heat pipe stageslongitudinally disposed within and along a length of an interior cavityof the outer body. Each heat pipe stage includes at least one internalheat pipe, wherein each internal heat pipe has an interior reservoirfilled with a working fluid structured to rapidly and efficientlytransfer heat from an evaporator end of the internal heat pipe to acondenser end of the respective internal heat pipe. Additionally, eachinternal heat pipe is longitudinally disposed within the interior cavityof the outer body such that the condenser end of each internal heat pipeof each stage is thermally coupled with the evaporator end of aninternal heat pipe of the longitudinally adjacent heat pipe stage.Therefore, heat absorbed at a first end of the outer body istransferred, via the internal heat pipe stages, to a second end of theouter body with a high rate of thermal efficiency.

Further areas of applicability of the present teachings will becomeapparent from the description provided herein. It should be understoodthat the description and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of the presentteachings.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present teachings in any way.

FIG. 1 is a side view of a composite heat pipe structure, in accordancewith various embodiments of the present disclosure.

FIG. 2 is a side cross-sectional view, along line A-A, of the compositeheat pipe shown in FIG. 1, in accordance with various embodiments of thepresent disclosure.

FIG. 3 is a sectional view, along line A-A, of the composite heat pipestructure shown in FIG. 1, in accordance with various embodiments of thepresent disclosure.

FIG. 3A is a sectional view, along line A-A, of the composite heat pipestructure shown in FIG. 1, rotated 90° from the view shown in FIG. 3, inaccordance with various embodiments of the present disclosure.

FIG. 4 is an end cross-sectional view, along line B-B, of the compositeheat pipe structure shown in FIG. 1, in accordance with variousembodiments of the present disclosure.

FIG. 5 is a partial view of two internal heat pipes of the compositeheat pipe structure shown in FIG. 1, thermally coupled by mini lateralheat pipes, in accordance with various embodiments of the presentdisclosure.

FIG. 5A is cross-sectional view, along line D-D, of the two internalheat pipes thermally coupled by mini lateral heat pipes, shown in FIG.5, in accordance with various embodiments of the present disclosure.

FIG. 6 is a cross-sectional side view of two internal heat pipes of thecomposite heat pipe structure shown in FIG. 1, thermally coupled by miniaxial heat pipes, in accordance with various embodiments of the presentdisclosure.

FIG. 6A is cross-sectional view, along line E-E of the two internal heatpipes thermally coupled by mini lateral heat pipes, shown in FIG. 5, inaccordance with various embodiments of the present disclosure.

FIG. 7 is a cross-sectional side view of two internal heat pipes of thecomposite heat pipe structure shown in FIG. 1, thermally interconnectedat distal ends, in accordance with various embodiments of the presentdisclosure.

FIG. 8 is side cross-sectional view of a composite heat pipe structure,such as that shown in FIG. 1, wherein the composite heat pipe structurecomprises a component of a motor, in accordance with various embodimentsof the present disclosure.

FIG. 8A is a cross-sectional view, along line C-C, of the composite heatpipe structure shown in FIG. 8, in accordance with various embodimentsof the present disclosure.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of drawings.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is in no wayintended to limit the present teachings, application, or uses.

Generally, in various embodiments, the present disclosure provides acomposite heat pipe structure that is structured to minimize the effectof gravity on the transfer of a condensed working fluid from a heatrejection, or condenser, end to a heat absorption, or evaporator, end ofconventional heat pipes. Minimizing the effect of gravity minimizes thelength restriction, especially in applications where the heatrejection/condenser end of a conventional heat pipe is below the heatabsorption/evaporator end. In various embodiments, the composite heatpipe structure can be constructed by integrating a plurality of internalheat pipes within an interior cavity of an outer body of heat pipestructure. The internal heat pipes are shorter and have a smallerdiameter than the outer body, and each has a respective evaporator endand condenser end. In various implementations, the internal heat pipescan be sequentially positioned in a longitudinally adjacent relationshipwithin the outer body such that the evaporator end of one or more of theinternal heat pipes will transfer heat to the condenser end of one ormore other internal heat pipes. This sequential positioning can berepeated multiple times to construct a composite heat pipe structure ofgenerally any desired length. To enhance the thermal connection betweenthe internal heat pipes, the outer body can be constructed of a highthermally conductive material.

The composite heat pipe structure can generally be any structure havingan outer body suitable for disposition of the internal heat pipes withinan internal cavity thereof. More specifically, the composite heat pipestructure can be any structure, machine or device from which heat needsto be removed and includes an outer body suitable for disposition of theinternal heat pipes within an internal cavity thereof, such as a motor,turbine, gear box, etc. For example, in various embodiments, thecomposite heat pipe structure can have an outer body in form of acylindrical pipe. Alternatively, in various embodiments, the compositeheat pipe structure can be a machine structure, device or componenthaving a body in the form of something other than a pipe. For example,in various embodiments, the heat pipe structure can be a motor, e.g., aliquid/oil cooled motor, whereby the liquid is cooled by the internalheat pipes disposed within the motor. As long as the composite heat pipestructure outer body is suitable to house the internal heat pipes suchthat heat can be transferred from the condenser end of one or moreinternal heat pipes to the evaporator end of one or more other internalheat pipes, as described below, the resulting composite heat pipestructure is within the scope of the present disclosure. Although thecomposite heat pipe structure outer body can have any suitable form, forclarity and simplicity, the composite heat pipe structure will beexemplarily illustrated and described herein as having the form of apipe. However, it should be understood that the scope of the presentdisclosure should not be so limited.

Referring now to FIGS. 1, 2, 3 and 3A, the present disclosure provides acomposite heat pipe structure 10 having an outer body 11. In the variousembodiments wherein the composite heat pipe structure 10 comprises apipe, the composite heat pipe structure 10 can additionally includeopposing end caps 13. For clarity and simplicity, the end caps 13 arenot shown in FIGS. 2, 3 and 3A. In various embodiments, the compositeheat pipe structure 10 includes a plurality of internal heat pipes,e.g., internal heat pipes 12, 12′, 14, 14′, 16, 16′, 18, 18′, 20 and20′, integrated within an interior cavity 21 of the outer body 11.Although the composite heat pipe structure 10 is shown to include teninternal heat pipes 12-20′, it should be understood that, in variousembodiments, the composite heat pipe structure 10 can include more thanor less than ten internal heat pipes and remain within the scope of thepresent disclosure. However, for clarity and simplicity, the compositeheat pipe structure 10 will be described herein as including teninternal heat pipes 12-20′.

Each of the internal heat pipes 12-20′ includes an interior reservoir 25filled with a working fluid, such as water, ethanol or mercury, thatwill evaporate, i.e., turn to a gaseous vapor state, when heated to aspecific evaporation temperature particular to the respective workingfluid. Additionally, as shown in FIG. 3A, each of the internal heatpipes 12-20′ respectively includes an evaporation end EE and an opposingcondenser end CE. Furthermore, each of the internal heat pipes 12-20′has a diameter that is smaller than the diameter of the outer body 11,and more particularly, has a longitudinal length that is shorter thanthat of the outer body 11. It should be understood that, although eachof the internal heat pipes 12-20′ are illustrated as having generallythe same diameter and length as all the other internal heat pipes12-20′, the diameter and/or length of various ones, or various pairs, ofvarious stages of the internal heat pipes 12-20′ can be different thanthe diameter and/or length of one or more of the other internal heatpipes 12-20′.

Generally, the composite heat pipe structure 10 includes a plurality of,i.e., two or more, internal heat pipe stages STG, e.g., STG1, STG2,STG3, STG4 and STG5, shown in FIG. 3. Each stage STG can include one,two, three or more internal heat pipes, e.g., internal heat pipes12-20′. Importantly, the internal heat pipe(s) of each stage STG, aredisposed within the cavity 21 in a head-to-foot relationship with theheat pipe(s) of the longitudinally adjacent stage STG. Accordingly, thecondenser end CE and/or evaporator end EE of each internal heat pipe ofeach stage STG is longitudinally adjacent the condenser end CE orevaporator end EE of at least one other internal heat pipe of at leastone longitudinally adjacent stage. More particularly, the condenser endCE and/or the evaporator end EE of each internal heat pipe of each stageSTG is in thermally conductive contact with, i.e., thermally coupled to,the condenser end CE or evaporator end EE of at least one respectiveinternal heat pipe of at least one longitudinally adjacent stage STG.Thus, the internal heat pipes 12-20′ are sequentially thermally coupledto each other in longitudinally adjacent relationship within the cavity21 such that heat absorbed at a first end 22 of the outer body 11 istransferred to a second end 23 of the outer body, via the internal heatpipes 12-20′.

For example, the internal heat pipes 12-20′ can be disposed within thecavity 21, such that the condenser end CE of each of the internal heatpipes 12-18′ is adjacent the evaporator end EE of at least one of therespective longitudinally adjacent internal heat pipes 14-20′. Moreover,in various embodiments, the condenser end CE of each of the internalheat pipes 12-18′ overlaps, i.e., extends past, and is laterallyadjacent the evaporator end EE of at least one of the respectivelongitudinally adjacent internal heat pipes 14-20′.

Referring now to FIGS. 3, 3A and 4, in various embodiments, each stageSTG of the composite heat pipe structure 10 includes a pair of internalheat pipes. For example, a first stage STG1 includes internal heat pipes12 and 12′, a second stage STG2 includes internal heat pipes 14 and 14′,a third stage STG3 includes internal heat pipes 16 and 16′, a fourthstage STG4 includes internal heat pipes 18 and 18′, and a fifth stageSTG5 includes internal heat pipes 20 and 20′. The stages STG1-STG5 arepositioned within the cavity 21 in a head-to-foot formation.

As illustrated, the condenser ends CE of the internal heat pipes 12 and12′ of the first stage STG1 are in thermally conductive contact with theevaporator ends EE of the internal heat pipes 14 and 14′ of the secondstage STG2. Additionally, the condenser ends CE of the internal heatpipes 14 and 14′ of the second stage STG2, are in thermally conductivecontact with the evaporator ends EE of the internal heat pipes 16 and16′ of the third stage STG3. Furthermore, the condenser ends CE of theinternal heat pipes 16 and 16′ of the third stage STG3 are in thermallyconductive contact with the evaporator ends EE of the internal heatpipes 18 and 18′ of the fourth stage STG4. Finally, the condenser endsCE of the internal heat pipes 18 and 18′ of the fourth stage STG4, arein thermally conductive contact with the evaporator ends EE of theinternal heat pipes 20 and 20′ of the fifth stage STG5.

In such embodiments, the pair of internal heat pipes 12 and 12′ of thefirst stage STG1 have their evaporator ends EE adjacent a first distalend 22 of the composite heat pipe structure 10, as shown in FIG. 2.Conversely, the internal heat pipes 20 and 20′ of the fifth stage STG5have their condenser ends CE adjacent a second distal end 23 of thecomposite heat pipe structure 10, as shown in FIG. 2.

In operation, heat at a first portion 21A of the cavity 21, i.e., heatat a first end of the composite heat pipe structure 10, will beabsorbed, or conducted, by the evaporator ends EE of the first stageSTG1 internal heat pipes 12 and 12′. The absorbed heat will cause theworking fluid inside the internal heat pipes 12 and 12′ at theevaporator ends EE to turn to vapor, thereby increasing the vaporpressure inside the internal heat pipes 12 and 12′. Subsequently, thevapor pressure at the evaporator ends EE of the internal heat pipes 12and 12′ will be higher than the equilibrium vapor pressure at thecondenser ends CE of the internal heat pipes 12 and 12′. The pressuredifference drives a rapid mass transfer of the heated vaporized workingfluid from the evaporator ends EE of the internal heat pipes 12 and 12′to the condenser ends CE of the internal heat pipes 12 and 12′ where thevapor condenses and releases its latent heat, thereby heating thecondenser ends CE of the internal heat pipes 12 and 12′. Thus, the heatabsorbed, or conducted, at the evaporator ends EE of the internal heatpipes 12 and 12′ is efficiently transferred, i.e., transferred withminimal thermal resistance, to the condenser ends CE of the internalheat pipes 12 and 12′.

Subsequently, via the thermally conductive contact between the condenserends CE of the first stage STG1 internal heat pipes 12 and 12′ and theevaporator ends EE of the adjacent second stage STG2 internal heat pipes14 and 14′, the heat from the condenser ends CE of the internal heatpipes 12 and 12′ is efficiently transferred to the evaporator ends EE ofthe adjacent internal heat pipes 14 and 14′. The heat from theevaporator ends EE of the internal heat pipes 14 and 14′ is thenefficiently transferred to the condenser ends CE of the internal heatpipes 14 and 14′, as described above with regard to internal heat pipes12 and 12′. In the same manner, the heat transferred to the condenserends CE of the second stage STG2 internal heat pipes 14 and 14′ istransferred to the evaporator ends EE of third stage STG3 internal heatpipes 16 and 16′ and then efficiently transferred to the condenser endsCE of the internal heat pipes 16 and 16′. Continuing in the same manner,the heat transferred to the condenser ends CE of the third stage STG3internal heat pipes 16 and 16′ is transferred to the evaporator ends EEof the fourth stage STG4 internal heat pipes 18 and 18′ then efficientlytransferred to the condenser ends CE of the internal heat pipes 18 and18′. Finally, the heat transferred to the condenser ends CE of thefourth stage STG4 internal heat pipes 18 and 18′ is transferred to theevaporator end EE of fifth stage STG5 internal heat pipes 20 and 20′ andthen efficiently transferred to the condenser ends CE of the internalheat pipes 20 and 20′, whereby the heat can be dissipated at a secondportion 21B of the cavity 21, i.e., a second end of the composite heatpipe structure 10.

Accordingly, the heat absorbed, or conducted, at the evaporator ends EEof the first stage STG1 internal heat pipes 12 and 12′ is transferred tothe condenser ends CE of the fifth stage STG5 internal heat pipes with ahigh level of thermal efficiency. More specifically, heat from the firstend of the composite heat pipe structure 10 is transferred to the secondend of the composite heat pipe structure 10 a high level of thermalefficiency. As used herein, the term thermal efficiency refers to theability to transfer large amounts of heat with very low thermalresistance which results in transfer of large amounts of heat with verysmall differences in temperature.

Although the composite heat pipe structure 10 is exemplarily illustratedand described herein as including five stages, i.e., stages STG1-STG5,it should be understood that it is envisioned that the composite heatpipe structure 10 can include more than, or less than five stages. Forexample, the composite heat pipe structure 10 can include two, three,four, five, six or more stages and remain within the scope of thepresent disclosure. Additionally, although each of the stages, e.g.,stages STG1-STG5, have been exemplarily illustrated and described hereinas including a pair of, i.e., two, internal heat pipes, it should beunderstood that each stage can include more than or less than a pair ofinternal heat pipes and remain within the scope of the presentdisclosure. For example, in various embodiments, each stage of thecomposite heat pipe structure 10 can include a single internal heatpipe, while in other embodiments each stage of the composite heat pipestructure 10 can include three, four, five or more internal heat pipes.Accordingly, the performance of the composite heat pipe structure 10 canbe enhanced by increasing the number of internal heat pipes disposedwithin the cavity 21, as described above. The number of internal heatpipes can be increased by utilizing internal heat pipes that are shorterin length and/or smaller in diameter.

Referring particularly to FIG. 4, in various embodiments, the compositeheat pipe structure 10 further includes a heat conductive medium 26disposed within the cavity 21 and surrounding the internal heat pipes12-20′. The heat conductive medium 26 is disposed within the cavity 21such that it is in thermally conductive contact with each of theinternal heat pipes 12-20′. Therefore, the heat conductive medium 26will efficiently transfer heat from the condenser ends CE of theinternal heat pipes 12-18′ to the respective evaporator ends EE of theinternal heat pipes 14-20′. The heat conductive medium 26 can be anysuitable substance, e.g., a solid, a gas, a liquid, paste, a foam, etc.,having high thermally conductive properties that will efficientlytransfer heat between the adjacent internal heat pipes 12-20′, asdescribed above. For example, in various embodiments, the heatconductive medium 26 can be a highly conductive metal such as copper orsilver; a highly conductive thermal grease and/or paste, e.g., compoundsspecifically designed to transfer heat that can include solid metalparticles such as copper and/or silver; and highly conductive liquidssuch as water, glycols and various types of oil.

In such embodiments, the combination of the thermally conductive outerbody 11, the highly efficient heat transfer characteristics of theinternal heat pipes 12-20′, and the highly thermally conductive medium26 will transmit heat in parallel paths to maximize the thermalconductivity of the composite heat pipe structure.

Referring now to FIGS. 5 and 5A, in various embodiments, the compositeheat pipe structure 10 can include a plurality of mini lateral heatpipes 24 disposed within the cavity 21 and thermally connecting thecondenser ends CE of the internal heat pipes 12-20′ to the respectiveevaporator ends EE of the internal heat pipes 14-20′. For clarity andsimplicity, FIGS. 5 and 5A exemplarily illustrates the mini lateral heatpipes 24 thermally connecting the condenser end CE of internal heat pipe12 with the evaporator end EE of adjacent internal heat pipe 14,however, it should be understood that the condenser end CE of eachinternal heat pipe can be thermally coupled to the evaporator end EE ofthe respective adjacent internal heat pipe, via the mini lateral heatpipes 24.

The mini lateral heat pipes 24 are structured substantially the same asthe internal heat pipes 12-20′, described above, only having smalldimensions and having a curvature such that they at least partially wraparound the outer surface of the respective internal heat pipes.Additionally, in various embodiments, the mini lateral heat pipes 24 canbe banded about, and secured to, the respective internal heat pipecondenser ends CE and evaporator ends EE via a housing 40.Alternatively, the mini lateral heat pipes 24 can be secured to, orcoupled to, the internal heat pipes via any suitable method, means ordevice, e.g., via welding, soldering, or other fastening devices.

In various embodiments, a cavity 42, formed between the housing 40 andthe respective internal heat pipes can be filled with a heat conductivemedium 44 to enhance the transfer of heat from the respective internalheat pipe condenser end CE to the respective internal heat pipeevaporator end EE, as described above. The heat conductive medium 44 canbe any suitable substance, e.g., a solid, a gas, a liquid, paste, afoam, etc., having high thermally conductive properties that willefficiently transfer heat between the adjacent internal heat pipes. Forexample, in various embodiments, the heat conductive medium 44 can be ahighly conductive metal such as copper or silver; a highly conductivethermal grease and/or paste, e.g., compounds specifically designed totransfer heat that can include solid metal particles such as copperand/or silver; and highly conductive liquids such as water, glycols andvarious types of oil.

Accordingly, in such embodiments, the mini lateral heat pipes 24efficiently transfer heat between the adjacent condenser ends CE andevaporator end EE of the adjacent internal heat pipes, e.g., internalheat pipes 12 and 14, as described above.

Referring now to FIGS. 6 and 6A, the internal heat pipes, e.g., internalheat pipes 12 and 14, of adjacent stages, e.g., the first and secondstages STG1 and STG2, can be disposed within the cavity 21 in a coaxialorientation. In such embodiments, the composite heat pipe structure 10can include a plurality of mini axial, or longitudinal, heat pipes 46disposed within the cavity 21 to thermally connect the condenser ends CEof the internal heat pipes 12-20′ to the respective evaporator ends EEof the internal heat pipes 14-20′. For clarity and simplicity, FIGS. 6and 6A exemplarily illustrates the mini axial heat pipes 46 thermallyconnecting the condenser end CE of internal heat pipe 12 with theevaporator end EE of adjacent internal heat pipe 14, however, it shouldbe understood that the condenser end CE of each internal heat pipe canbe thermally coupled to the evaporator end EE of the respective adjacentinternal heat pipe, via the mini axial heat pipes 46.

The mini axial heat pipes 46 are structured substantially the same asthe internal heat pipes 12-20′, described above, only having smalldimensions, i.e., smaller diameters and lengths. Additionally, invarious embodiments, the mini axial heat pipes 46 can be banded about,and secured to, the respective internal heat pipe condenser ends CE andevaporator ends EE via a housing 48. Alternatively, the mini axial heatpipes 46 can be secured to, or coupled to, the internal heat pipes viaany suitable method, means or device, e.g., via welding, soldering, orother fastening devices.

In various embodiments, a cavity 50, formed between the housing 48 andthe respective internal heat pipes can be filled with a heat conductivemedium 52 to enhance the transfer of heat from the respective internalheat pipe condenser end CE to the respective internal heat pipeevaporator end EE, as described above. The heat conductive medium 52 canbe any suitable substance, e.g., a solid, a gas, a liquid, paste, afoam, etc., having high thermally conductive properties that willefficiently transfer heat between the adjacent internal heat pipes. Forexample, in various embodiments, the heat conductive medium 52 can be ahighly conductive metal such as copper or silver; a highly conductivethermal grease and/or paste, e.g., compounds specifically designed totransfer heat that can include solid metal particles such as copperand/or silver; and highly conductive liquids such as water, glycols andvarious types of oil.

Accordingly, in such embodiments, the mini axial heat pipes 46efficiently transfer heat between the adjacent condenser ends CE andevaporator end EE of the adjacent internal heat pipes, e.g., internalheat pipes 12 and 14, as described above.

Referring now to FIG. 7, in various embodiments, the internal heatpipes, e.g., internal heat pipes 12 and 14, of adjacent stages, e.g.,the first and second stages STG1 and STG2, can be disposed within thecavity 21 in a coaxial orientation and be physically and thermallyinterconnected with the respective condenser ends CE and evaporator endsEE. For example, in various embodiments, each internal heat pipe isstructured such that the condenser end CE has an outside diameter thatis smaller than the outside diameter of a central portion CP of therespective internal heat pipe, thereby providing a male node 54 at thecondenser end CE of each internal heat pipe. Furthermore, in suchembodiments, each internal heat pipe is structured such that theevaporator end EE has a inside diameter that is smaller than the outsidediameter of the central portion CP, thereby providing a female nodereceptacle 56 at the evaporator end EE of each internal heat pipe.

Moreover, in such embodiments, each internal heat pipe is structuredsuch that the inside diameter of each female node receptacle 58 issubstantially the same as the outside diameter of each male node 54.Therefore, the internal heat pipes can be securely physically andthermally interconnected within the cavity 21 by inserting the male node54 of each of the internal heat pipes into the female node receptacle 56of the respective adjacent internal heat pipes.

For clarity and simplicity, FIG. 7 exemplarily illustrates the physicaland thermal interconnection of the condenser end CE of internal heatpipe 12 with the evaporator end EE of adjacent internal heat pipe 14,however, it should be understood that the condenser end CE of each ofthe internal heat pipe 12-18′ can be physically and thermally coupled tothe evaporator end EE of the respective adjacent internal heat pipes14-20′, via the male nodes 54 and the female node receptacles 56, asdescribed above.

The male nodes 54 and female node receptacles 56 can be securelyphysically and thermally interconnected utilizing any suitableconnection method, means or device. For example, the male nodes 54 andfemale node receptacles 56 can be securely physically and thermallyinterconnected utilizing a substantially tight friction fit, utilizingmating threads formed within the male nodes 54 and female nodereceptacles 56, by welding or soldering the male nodes 54 within thefemale node receptacles 56, etc.

In various implementations of such embodiments, each internal heat pipecan include an interior wall (not shown) at the evaporator end of thecentral portion CP. Accordingly, the interior reservoir 25 of eachinternal heat pipe is formed between the interior wall and the interiorside of the distal end of the respective male node 54. Thus, a closedcircuit for the working fluid is provided within the cavity 25 formedbetween the interior wall and the interior side of the distal end of therespective male node 54. Alternatively, the evaporator end of thecentral portion CP of each internal heat pipe can be open, i.e., absentthe interior wall, such that each respective interior reservoir 25 isformed only when the male node 54 of the adjacent internal heat pipe issecurely physically and thermally interconnected with the female nodereceptacle 56 of the respective internal heat pipe, as described above.Thus, a closed circuit for the working fluid is provided within thecavity 25 formed when the male node 54 of the adjacent internal heatpipe is securely physically and thermally interconnected with the femalenode receptacle 56 of the respective internal heat pipe.

Alternatively, in various embodiments, the composite heat pipe structurecan comprise a plurality of short sections, absent the internal heatpipes, that are physically and thermally interconnected, via male nodesand female node receptacles, such as those described above with regardto the internal heat pipes illustrated in FIG. 7.

Referring now to FIGS. 8 and 8A, as described above, the composite heatpipe structure 10 can be any structure, machine or device from whichheat needs to be removed and includes an outer body suitable fordisposition of the internal heat pipes within an internal cavitythereof, such as a motor, turbine, gear box, etc. For example, asexemplarily illustrated in FIGS. 8 and 8A, in various embodiments thecomposite heat pipe structure 10 can comprise a portion of a motor.

In such embodiments, the outer body 11 comprises a frame 28 and end cap29 of the motor 10 and the cavity 21 comprises the space between theouter body 11, i.e., frame 28 and end cap 29, and a stator assembly 30of the composite heat pipe structure/motor 10. FIGS. 8 and 8Aexemplarily illustrate the composite heat pipe structure 10 of suchembodiments to include three stages, i.e., the first STG1, the secondSTG2 and the third STG3. Each stage STG1, STG2 and STG3 includes aplurality of internal heat pipes 32, 34 and 36, respectively, that arestructured substantially the same as the internal heat pipes 12-20′,described above.

The internal heat pipes 32, 34 and 36 are disposed around, and inthermally conductive contact with, the stator assembly 30 within thecavity/space 21 such that the condenser end CE of each internal heatpipe 32 is in thermally conductive contact with the evaporator end EE ofa respective one or more of the internal heat pipes 34. Similarly, thecondenser end CE of each internal heat pipe 34 is in thermallyconductive contact with the evaporator end EE of a respective one ormore of the internal heat pipes 36. Accordingly, heat from a firstportion 21A of the cavity/space 21 will be efficiently transferred to asecond portion 21 B of the cavity/space 21, via the internal heat pipes32, 34 and 36, as described above with regard to internal heat pipes12-20′.

As illustrated in FIGS. 8 and 8A, in various embodiments, the internalheat pipes 32, 34 and 36 can be disposed within a back iron ring (BIR)38 that is disposed within the cavity/space 21. The BIR 38 is structuredto house the internal heat pipes 32, 34 and 36 to provide support andstability of the internal heat pipes 32, 34 and 36 within thecavity/space 21. In various implementations, the BIR 38 can furtherprovide a heat conductive medium, such as the heat conductive medium 26described above, to enhance the efficient transfer of heat between theinternal heat pipes 32, 34 and 36.

Using simulations, an example of the thermal efficiency of the compositeheat pipe structure 10, as described herein, will now be provided. Theexample includes an instance wherein the composite heat pipe structureis 0.625″ in diameter and 24″ in length. Similar to the composite heatpipe structure 10 illustrated in FIGS. 2, 3, and 3A, the examplecomposite heat pipe structure includes five stages of internal heatpipes, for a total of 10 internal heat pipes. Two inches of overlap isimplemented between each stage of internal heat pipes to providethermally conductive contact between the internal heat pipes of onestage and the internal heat pipes of the adjacent stage. A thermallyconductive medium that fills the entire internal cavity of the compositeheat pipe structure is implemented, which transfers the heat between theadjacent stages of internal heat pipes.

The table below compares simulated performance of traditional heat pipesto the example composite heat pipe structure described above:

¼″ by 6″ ¼″ by 24″ ⅝″ by 24″ ⅝″ by 24″ single heat single heat singleheat composite heat Orientation pipe pipe pipe pipe Horizontal 68 W 17 W 33 W 136 W Vertical 98 W 47 W 110 W 196 W (evaporator down) Vertical 38W  0 W  0 W  76 W (evaporator up)

As illustrated in the table above the composite heat pipe structure ofthe present disclosure provides high thermal efficiency in the transferof heat from the first end to the second end of the composite heat pipestructure.

Based on the present disclosure, one of ordinary skill in the art canreadily appreciate that multiple stages of internal heat pipes can beimplemented to create a composite heat pipe structure that overcomes thelength limitations of known single pipe heat pipes.

The description herein is merely exemplary in nature and, thus,variations that do not depart from the gist of that which is describedare intended to be within the scope of the teachings. Such variationsare not to be regarded as a departure from the spirit and scope of theteachings.

1. A composite heat pipe structure comprising: an outer body; aplurality of internal heat pipes sequentially disposed in alongitudinally adjacent relationship within an interior cavity of theouter body such that internal heat pipes are sequentially thermallycoupled to one another along a portion of each respective internal heatpipe so that heat absorbed at a first end of the outer body istransferred to a second end of the outer body, via the internal heatpipes, with a high rate of thermal efficiency.
 2. The structure of claim1, wherein the outer body comprises cylindrical pipe.
 3. The structureof claim 1, wherein the outer body comprises a frame and end cap of amotor and the interior cavity comprises a space between the frame andend cap, and a stator assembly of the motor.
 4. The structure of claim1, wherein the outer body comprises a portion of a turbine housing andthe interior cavity comprises a space within the turbine housing.
 5. Thestructure of claim 1, wherein the outer body comprises a portion of agearbox housing and the interior cavity comprises a space within thegearbox housing.
 6. The structure of claim 1, wherein the structurefurther comprises a heat conductive medium disposed within the interiorcavity and surrounding the internal heat pipes, whereby the heatconductive medium improves the efficiency of a transfer of heat betweenthe thermally coupled longitudinally adjacent heat pipes.
 7. Thestructure of claim 1, wherein the structure further comprises aplurality of mini lateral heat pipes disposed within the interior cavityand thermally connecting the longitudinally adjacent heat pipes, wherebythe mini lateral heat pipes improve the efficiency of a transfer of heatbetween the thermally coupled longitudinally adjacent heat pipes.
 8. Thestructure of claim 1, wherein the structure further comprises aplurality of mini axial heat pipes disposed within the interior cavityand thermally connecting the longitudinally adjacent heat pipes, wherebythe mini axial heat pipes improve the efficiency of a transfer of heatbetween the thermally coupled longitudinally adjacent heat pipes
 9. Thestructure of claim 1, wherein each internal heat pipe comprises a malenode formed at a first end and a female node receptor formed at anopposing second end such that the internal heat pipes are sequentiallythermally coupled to one another by securely physically coupling themale node of each internal heat pipe into the female node receptacle ofthe respective longitudinally adjacent internal heat pipe.
 10. Thestructure of claim 1, wherein each internal heat pipe comprises aninterior reservoir filled with a working fluid structured to rapidly andefficiently transfer heat absorbed at an evaporator end of each internalheat pipe to a condenser end of the respective internal heat pipe.
 11. Acomposite heat pipe structure comprising: an outer body; a plurality ofinternal heat pipes longitudinally disposed within an interior cavity ofthe outer body such that a condenser end of each internal heat pipe isthermally coupled with an evaporator end of at least one longitudinallyadjacent internal heat pipe so that heat absorbed at a first end of theouter body is transferred to a second end of the outer body, via theinternal heat pipes, with a high rate of thermal efficiency.
 12. Thestructure of claim 11, wherein the outer body comprises cylindricalpipe.
 13. The structure of claim 11, wherein the outer body comprises aframe and end cap of a motor and the interior cavity comprises a spacebetween the frame and end cap, and a stator assembly of the motor. 14.The structure of claim 11, wherein the outer body comprises a portion ofa turbine housing and the interior cavity comprises a space within theturbine housing.
 15. The structure of claim 11, wherein the outer bodycomprises a portion of a gearbox housing and the interior cavitycomprises a space within the gearbox housing.
 16. The structure of claim11, wherein the structure further comprises a heat conductive mediumdisposed within the interior cavity and surrounding the internal heatpipes, whereby the heat conductive medium improves the efficiency of atransfer of heat between the thermally coupled condenser ends of theinternal heat pipes to the evaporator ends of the respectivelongitudinally adjacent heat pipes.
 17. The structure of claim 11,wherein the structure further comprises a plurality of mini lateral heatpipes disposed within the interior cavity and thermally connecting thecondenser ends of the internal heat pipes to the evaporator ends of therespective longitudinally adjacent heat pipes, whereby the mini lateralheat pipes improve the efficiency of a transfer of heat between thethermally coupled condenser ends and evaporator ends.
 18. The structureof claim 11, wherein the structure further comprises a plurality of miniaxial heat pipes disposed within the interior cavity and thermallyconnecting the longitudinally adjacent heat pipes, whereby the miniaxial heat pipes improve the efficiency of a transfer of heat betweenthe thermally coupled longitudinally adjacent heat pipes
 19. Thestructure of claim 11, wherein each internal heat pipe comprises a malenode formed at the condenser end and a female node receptor formed atevaporator end such that the internal heat pipes are sequentiallythermally coupled to one another by securely physically coupling themale node of each internal heat pipe into the female node receptacle ofthe respective longitudinally adjacent internal heat pipe.
 20. Thestructure of claim 11, wherein each internal heat pipe comprises aninterior reservoir filled with a working fluid structured to rapidly andefficiently transfer heat absorbed at the evaporator end of eachinternal heat pipe to the condenser end of the respective internal heatpipe.
 21. A composite heat pipe structure comprising: an outer body; aplurality of internal heat pipe stages longitudinally disposed withinand along a length of an interior cavity of the outer body, each heatpipe stage including: at least one internal heat pipe, each internalheat pipe having an interior reservoir filled with a working fluidstructured to rapidly and efficiently transfer heat from an evaporatorend of the internal heat pipe to a condenser end of the respectiveinternal heat pipe, and each internal heat pipe being longitudinallydisposed within the interior cavity of the outer body such that thecondenser end of the at least one internal heat pipe of each stage isthermally coupled with the evaporator end of a respective one of the atleast one internal heat pipe of the longitudinally adjacent heat pipestage so that heat absorbed at a first end of the outer body istransferred, via the internal heat pipe stages, to a second end of theouter body with a high rate of thermal efficiency.
 22. The structure ofclaim 21, wherein the outer body comprises cylindrical pipe.
 23. Thestructure of claim 21, wherein the outer body comprises a frame and endcap of a motor and the internal cavity comprises a space between theframe and end cap, and a stator assembly of the motor.
 24. The structureof claim 21, wherein the outer body comprises a portion of a turbinehousing and the interior cavity comprises a space within the turbinehousing.
 25. The structure of claim 21, wherein the outer body comprisesa portion of a gearbox housing and the interior cavity comprises a spacewithin the gearbox housing.
 26. The structure of claim 21, wherein thestructure further comprises a heat conductive medium disposed within thecavity and surrounding the heat pipe stages, whereby the heat conductivemedium improves the efficiency of a transfer of heat between thethermally coupled condenser ends and evaporator ends of the at least oneinternal heat pipe of each longitudinally adjacent heat pipe stage. 27.The structure of claim 21, wherein the structure further comprises aplurality of mini lateral heat pipes disposed within the cavity andthermally connecting the condenser ends and evaporator ends of the atleast one internal heat pipe of each longitudinally adjacent heat pipestage, whereby the mini lateral heat pipes improve the efficiency of atransfer of heat between the thermally coupled condenser ends andevaporator ends.
 28. The structure of claim 21, wherein the structurefurther comprises a plurality of mini axial heat pipes disposed withinthe interior cavity and thermally connecting the longitudinally adjacentheat pipes, whereby the mini axial heat pipes improve the efficiency ofa transfer of heat between the thermally coupled longitudinally adjacentheat pipes
 29. The structure of claim 21, wherein each internal heatpipe comprises a male node formed at the condenser end and a female nodereceptor formed at evaporator end such that the internal heat pipes aresequentially thermally coupled to one another by securely physicallycoupling the male node of each internal heat pipe into the female nodereceptacle of the respective longitudinally adjacent internal heat pipe.30. The structure of claim 21, wherein each heat pipe stage comprises asingle internal heat pipe.
 31. The structure of claim 21, wherein eachheat pipe stage comprises two or more internal heat pipes.